a. Field of the Invention
The present invention relates generally to hydraulic systems used in heavy equipment and the like, and, more particularly, to a clamp assembly for mounting hydraulic lines to the booms and arms of heavy equipment and similar structures.
b. Related Art
Hydraulic lines are commonly employed to supply hydraulic oil to actuators that operate the various components of heavy equipment and similar apparatus. For example, such lines are commonly used to supply oil to hydraulic cylinders and rams for operating various parts and systems on earth-moving and land-clearing equipment. Typically, the hydraulic lines are constructed of lengths of rigid steel tubing that are joined by hoses where flexible connections are required.
For example, FIG. 1 shows an exemplary articulated excavator arm 10 having a bucket 12 mounted on its outer end. The bucket is provided with a xe2x80x9cthumbxe2x80x9d attachment 14 which is operated by a hydraulic cylinder 16. Hydraulic pressure is applied to the cylinder from a remote source (e.g., hydraulic pump mounted on a main chassis) via rigid hydraulic lines 20 and flexible hoses 22.
As can be seen in FIG. 1, the rigid hydraulic lines 20 are secured to the segments 24, 26 of the articulated arm by mounting clamps 28. It is important for the clamps to hold the lines tightly to the arm, in order to prevent the lines from hanging loose and becoming caught on external objects or otherwise being damaged during use. Furthermore, the clamps must hold the hydraulic lines against longitudinal movement in order to prevent the lines from xe2x80x9ccreepingxe2x80x9d and working loose in response to internal pressure changes.
In some original equipment manufacturer (OEM) installations, these problems are dealt with using a mounting structure that is welded to the support boom and sometimes directly to the hydraulic line itself. In other installations, however, there is a need for a device for detachably mounting the hydraulic lines to the support structure, or for subsequently attaching one or more additional lines in a convenient and secure manner. This is especially true in the case of after-market attachment that are added to existing equipment, such as the thumb attachment 14 which is shown in FIG. 1, for example.
One type of device which is used for this purpose is a bolt-on clamp assembly, which has the advantage of relatively easy installation and/or removable. Moreover, the bolt-on clamp assemblies can often be used to xe2x80x9cpiggy backxe2x80x9d on existing OEM mounts: the original mounting bolt is removed and the after-market clamp is placed on top of the OEM bracket or clamp, and then a new, longer bolt is passed through both clamps to secure the assembly to the support structure.
While advantageous for the reasons described above, prior forms of bolt-on clamp assemblies have generally been less than satisfactory in one respect or another. To illustrate this, FIGS. 2A-2B show a prior art clamp assembly 30, of a type that is used by several manufacturers. As can be seen, the clamp assembly includes upper and lower members 32, 34, which are typically formed of ordinary cast steel. The clamp members are mounted to the underlying support structure 36 by a bolt 40 that passes through corresponding bores 42, 44 and is threaded into a cooperating bore in the underlying structure. Upper and lower generally concave jaw portions 46, 48 are located to one side of the bolt and are configured for receiving a rigid hydraulic line 50 having a corresponding diameter. On the opposite side of the mounting bolt, the edge of the upper member extends downwardly to form a pointed flange 52 which bears against the upper surface 54 of the lower clamp member so as to form a fulcrum 56. Thus, as bolt 40 is tightened, the downward pressure which is inserted by the head of the bolt against the upper surface 58 of the upper clamp member 32 causes the jaw portion 46 to pivot downwardly in the direction indicated by arrow 60, thus exerting a clamping force against hydraulic line 50.
One deficiency of clamps of the type shown in FIGS. 2A-2B is that the location of the bolt between the fulcrum and the jaw portions results in a reduced mechanical advantage, i.e., the grip force which is exerted at the jaw portions is actually less than that which is exerted by the bolt against the clamp members. This type of clamp is also cumbersome and difficult to use, being that the upper and lower members tend to twist relative to one another until they move into engagement with the hydraulic line, so that the assembly tends to xe2x80x9cflopxe2x80x9d about and become misaligned during installation.
Perhaps more seriously, the jaw portions of such clamps tend to deform and crush the hydraulic line as the assembly is tightened, which is undesirable from the standpoint of reducing flow and compromising the structural integrity of the line, amongst other reasons. This problem is compounded by the fact that the jaw portions, with their pincer-like movement, are only able to engage limited areas along the top and bottom of the hydraulic line, which impairs their ability to establish frictional engagement with the line; as was noted above, it is important for the clamp to hold the hydraulic line against longitudinal xe2x80x9ccreepingxe2x80x9d motion, as well as against motion in lateral directions. As a result, the tendency is for the operator to tighten the bolt even further in an effort to stop longitudinal movement of the hydraulic line, thereby increasing the deformation and damage to the line.
In some instances, manufacturers have resorted to the expedient of installing a plastic or rubber insert between the jaws in an effort to reduce damage to the hydraulic lines. Unfortunately, the inserts tend to slip against the hydraulic lines, with the result that longitudinal movement/creep of the lines increases unacceptably. Furthermore, the plastic/rubber inserts tend to melt when subjected to the high temperatures that hydraulic lines develop in many types of machinery.
Accordingly, there exists a need for a bolt-on clamp assembly for mounting hydraulic lines to a support structure that establishes a firm grip against the hydraulic line without causing deformation or crushing of the line. Furthermore, there exists a need for such a clamp assembly that avoids deformation/crushing of hydraulic lines without need for an elastomeric or deformable insert. Still further, there exists a need for such a clamp assembly that establishes a firm frictional engagement with hydraulic lines so as to prevent longitudinal movement of the lines relative thereto. Still further, there exists a need for such a clamp assembly that is mechanically efficient so as to avoid the need for over-tightening the mounting bolt which secures the assembly to the support structure. Still further, there exists a need for such a clamp assembly in which the clamp members thereof are linked in stable relationship with respect to one another so as to avoid twisting and/or misalignment during installation.
The present invention has solved the problems cited above, and is a bolt-on clamp assembly for mounting a hydraulic line to a support structure.
Broadly, the clamp assembly comprises upper and lower clamp members, the upper clamp member having a downwardly facing jaw portion and the lower clamp member having an upwardly facing jaw portion, so that the jaw portions define a receiving area for engaging a hydraulic line therein; a mounting portion located to one side of the receiving area for passage of a mounting bolt therethrough; and a hinge structure interconnecting the upper and lower clamp members so as to form an upwardly-directed fulcrum on a side of the receiving area opposite the mounting portion, so that the upper clamp member pivots about the upwardly-directed fulcrum in response to tightening of the mounting bolt so as to exert a downwardly directed clamping force against the hydraulic line in the receiving area.
The hinge structure interconnecting the upper and lower clamp members may comprise an upwardly-projecting flange portion formed along the edge of the upper clamp member, and a downwardly facing channel portion formed along an edge of the lower clamp member for receiving the upwardly projecting flange in pivoting engagement therewith, so as to form the upwardly-directed fulcrum and also prevent the upper clamp member from twisting relative to the lower clamp member. The mounting portion may comprise first and second co-axially aligned bores formed in the upper and lower clamp members for passage of the mounting bolt therethrough.
The clamp assembly may further comprise means for limiting the pivoting motion of the upper clamp member to a predetermined range so as to prevent the hydraulic line from being crushed or deformed between the jaw portions of the members. The means for limiting the pivoting motion of the upper clamp member may comprise a first stop face formed on a lower surface of the upper clamp member and a second stop face formed on an upper surface of the lower clamp member in opposition to the first stop face, the first and second stop faces being spaced apart by a pinch gap of predetermined width when a hydraulic line of predetermined diameter is received between the jaw portions of the upper and lower clamp members.
The upper clamp member may further comprise a downwardly-extending flange portion formed on an edge of the upper clamp member opposite the upwardly-projecting flange portion, so that the downwardly-extending flange portion bears against an underlying support surface so as to provide a fulcrum point on the opposite side of the mounting bolt from the jaw portion when the upper clamp member is used as a single-piece clamp without the lower clamp member. The lower clamp member may further comprise a corresponding recess for receiving the downwardly projecting flange portion of the upper clamp member therein.
The jaw portions of the upper and lower clamp members may each have a substantially hemicylindrical contour, so that the jaw portions engage the hydraulic line about substantially the entire circumference thereof.
The upper and lower clamp members may have a substantially uniform cross-section in a direction parallel to the cylindrical axis of the jaw portions, so that the clamp members may be formed of extruded material, such as high strength extruded aluminum alloy.
The invention also provides a hydraulically operated apparatus having a bolt-on clamp assembly for mounting a hydraulic line to a support member, in which the support member may be, for example, a segment of an articulated arm of the apparatus. The support structure may also be an outwardly extending bracket for supporting the hydraulic line at a spaced distance from the arm or other portion of the hydraulically powered apparatus.
These and other features and advantages of the present invention will be more fully understood from a reading of the following detailed description with reference to the associated figures.